Impaction and Wear-Resistant Carbon Elastic Seal for HTHP Downhole Valve Application

Abstract

In this work, an elastic carbon composite, a new category of high-pressure/high-temperature (HPHT) seal material, was developed and its successful application in downhole valves is discussed to demonstrate how it could address sealing challenges in HTHP and sour wells exploration. As conventional oil and gas resources decline, exploration and production (E&P) activity increasingly involves operations in extreme HPHT conditions and corrosive sour environments (high in H2S and CO2), posing tremendous challenges on almost all aspects from drilling to completion and production. One of these challenges is developing reliable seals for various kinds of downhole valves, e.g., safety valves, chemical injection valves, pressure relief valves, etc., that must withstand HPHT and sour environments and must work under frequent impact and wear caused by operation or sands from downhole fluids. Under HT conditions (usually above 500° F), current valve seals made of plastic or rubber are no longer suitable, because the material loses its mechanical strength and becomes very soft. Therefore, these seal can easily extrude and fail under pressure. Metal-to-metal seals may perform better in HPHT conditions, but they have a very high failure rate due to low elasticity and high metallic hardness. To address this issue, an elastic carbon composite, a new category of HPHT seal material, was developed. Material tests show that this novel carbon composite material has excellent thermal stability up to 1,000° F and strong resistance to impact and wear. This paper discusses the material property of this novel elastic carbon composite. The application of the material in a chemical injection valve is also be provided as an example to show how this new composite addresses downhole seal challenges for valve applications. The novelty of this work is developing a new seal material that could enable downhole valve work at extreme HPHT conditions. Related knowledge and information of this work would benefit engineer in developing new technologies for various downhole valve tools.

Casing structural integrity and failure modes in a range of well types - A review

“…A new promising composite material called elastic carbon composite (ECC) is developed recently to overcome the challenge of high temperature differentials which occur in HPHT and steam injection wells. ECC have good thermal stability with resistant to corrosion at temperatures up-to 538°C or 281°C (Zhao et al, 2017;Xu et al, 2017). This new sealing element have demonstrated capacity in terms of both sealing and chemical resistance to downhole fluids than commercial graphite seal.…”